A wide variety of pop-up sprinklers are known where a housing is typically buried under. ground surface where the sprinkler is concealed for both aesthetic reasons and for practical ones, e.g. to facilitate easy lawn mooring, to prevent the sprinkler from being an obstacle to pedestrians, etc. In some cases a pop-up sprinkler is intended for increasing the irrigation range, or for over coming obstacles such as a bush, a decorative stone, a fence, etc. These objects are however achieved by a substantially large housing with a corresponding long pop-up stem member, requiring suitable sealing means.
A different type of pop-up sprinklers is of the kind comprising a membrane deformable between a retracted position and an elevated position, responsive to water supply pressure. Such sprinklers are described, for example, in U.S. Pat. No. 3,282,508 to Bailey and U.S. Pat. No. 4,919,332 to Roberts.
It is an object of the present invention to provide a pop-up sprinkler fitted with an improved raising mechanism which, on the one hand, is inexpensive and easy to assemble and, on the other hand, offers many advantages such as compact structure, smooth and trouble-free operation, insect and dirt protection, inverted installation (‘top down’), etc. Furthermore, the sprinkler according to the present invention offers much diversity for various purposes. For example, the sprinkler may be integrally fitted with a flow control assembly and a leak-preventing device, with an in-line filter, etc.